1. Field of the Invention
This invention relates to an improvement in a combustion cylinder construction which is adapted to be used for an oil burner of the type of radiating heat rays from an outer cylindrical member of a double combustion cylinder red-heated and radiating light rays and heat rays from a white-yellow flame formed at a flame spreading means arranged in a combustion chamber, and more particularly to such a combustion cylinder construction constructed to allow combustion air to be fed from a space between the outer cylindrical member and a heat-permeable cylinder to the flame spreading means.
2. Description of the Prior Art
A combustion cylinder construction has been extensively used for an oil burner which is constructed in such a manner that a top plate of an outer cylindrical member acts also as a bottom plate of a combustion chamber having a flame spreading means arranged therein and combustion air to be fed to the outside of the flame spreading means is introduced from a space between the outer cylindrical member and a heat-permeable cylinder. Such a conventional combustion cylinder construction has an advantage that an outer wall of the combustion chamber may be formed integral with the heat-permeable cylinder, because the construction does not require the introduction of combustion air from the exterior thereof. However, in the construction, the wall of the combustion chamber or the upper portion of a heat-permeable cylinder is adhered thereto whity fine particles resulting from the combustion of impurity contained in fuel oil and/or fine particles of carbon generated due to the incomplete combustion to substantially reduce efficiency in heat radiation through the heat-permeable cylinder. In order to avoid such adhesion, the construction is constructed to pass air through the overall inner surface of the wall of the combustion chamber to prevent the fine particles from contacting with the inner surface. This is typically carried out by extending the top plate of the outer cylindrical member in proximity to the heat-permeable cylinder to form an annular gap between the heat-permeable cylinder and the top plate and allowing a part of combustion air to upward flow from the space between the outer cylindrical member and the heat-permeable cylinder through the gap along the overall inner surface.
However, the conventional combustion cylinder construction adapted to feed combustion air from the space between the outer cylindrical member and the heat-permeable cylinder as described above has an important disadvantage that the maximum combustion and the control of combustion are substantially restricted, as compared with a combustion cylinder construction which is adapted to introduce combustion air from the exterior thereof directly to a flame spreading means.
More particularly, a draft in a combustion cylinder means of such a multi-cylinder combustion construction as described above is varied depending upon the combustion in the construction, whereas a draft in a combustion chamber defined above the combustion cylinder means or in the upper portion of the construction is most predominantly generated near a flame spreading means and also varied depending upon the combustion in the construction. Thus, it will be noted that a draft in the construction has a correlation with the variation in heat value at the time of adjusting the combustion, resulting in normal combustion being kept within a certain range even when the adjustment of combustion is carried out. A draft in the portion of the combustion chamber except the vicinity of the flame spreading means cannot be substantially varied depending upon combustion in the construction, as compared with those in the combustion cylinder and near the flame spreading means. Thus, air fed from a slit formed at the bottom plate of the combustion cylinder or the gap between the top plate of the outer cylindrical member and the heat-permeable cylinder toward the inner surface of the cylindrical wall of the combustion chamber is slowly varied with respect to the variation of combustion in the construction. Such a draft in the combustion chamber significantly affects a draft in the space between the outer cylindrical member and the heat-permeable cylinder via the slit of the bottom plate of the combustion chamber to cause the latter draft to be kept still strong even when the rate of combustion is small. This also does not allow a desired draft to be obtained at the maximum combustion.